Multithreaded File/Folder Finder

using System;
using System.Collections;
using System.Management;

namespace FileFind
{
    class LogicalPhysicalDiskResolution
    {
        /// <summary>
        /// Group logical disks being searched with other logical disks on the same physical disk.
        /// This will speed the search by reducing contention on the drive.
        /// Logical drives not being searched are not included in the return list.
        /// ResolvePartitions runs asynchronously via BeginInvoke/EndInvoke
        /// </summary>
        /// <param name="selectedDrives">Disks selected to be searched.
        /// Each entry contains one drive letter in the form of C:\, D:\, etc</param>
        /// <returns>Drive letter desinations are returned as single entry or
        /// multiple letters when logical partitions are on the same physical drive.
        /// A multipartitioned drive will show as a single if the other partition(s)
        /// on the physical is not being searched.
        /// Example return list:
        /// C:\;D:\
        /// E:\
        /// </returns>
        public ArrayList ResolvePartitions(ArrayList selectedDrives)
        {
            ArrayList readyDrives = new ArrayList(selectedDrives);
            ArrayList resolvedDrives = new ArrayList();
            ArrayList partitionedDrives = GetPartitionInfo();
            if (partitionedDrives == null)
                resolvedDrives = readyDrives;
            else
            {
                foreach (string partition in partitionedDrives)
                {
                    string part = null;
                    string[] str = partition.Split(new char[1] { ';' });
                    foreach (string partitionName in str)
                    {
                        if (readyDrives.Contains(partitionName))
                        {
                            readyDrives.Remove(partitionName);
                            if (String.IsNullOrEmpty(part))
                                part = partitionName;
                            else
                                part += ";" + partitionName;
                        }
                    }
                    if (null != part)
                        resolvedDrives.Add(part);
                }
                if (readyDrives.Count != 0)
                {
                    foreach (string readyDrive in readyDrives)
                        resolvedDrives.Add(readyDrive);
                }
            }
            return resolvedDrives;
        } //ends private ArrayList ResolvePartitions(...

        /// <summary>
        /// Find all physical drives and identify the partitions by letter desinations.
        /// All logical drives are returned even if they are not to be searched.
        /// </summary>
        /// <returns>Drive letter desinations are returned as C:\;D:\ or E:\ where
        /// C: and D: are on the same physical drive and E: is on a drive by itself.</returns>
        private ArrayList GetPartitionInfo()
        {
            ArrayList partitionedDrives = new ArrayList();
            try
            {
                ManagementObjectSearcher searcher = new
                       ManagementObjectSearcher("SELECT * FROM Win32_DiskDrive");

                foreach (ManagementObject wmi_HD in searcher.Get())
                {   //physical disk drives
                    string driveLetter = null;
                    foreach (ManagementObject partition in new ManagementObjectSearcher(
                "ASSOCIATORS OF {Win32_DiskDrive.DeviceID='"
                + wmi_HD["DeviceID"]
                + "'} WHERE AssocClass = Win32_DiskDriveToDiskPartition").Get())
                    {   //logical disk drives
                        foreach (ManagementObject disk in new ManagementObjectSearcher(
                        "ASSOCIATORS OF {Win32_DiskPartition.DeviceID='"
                        + partition["DeviceID"]
                        + "'} WHERE AssocClass = Win32_LogicalDiskToPartition").Get())
                        {
                            if (String.IsNullOrEmpty(driveLetter))
                                driveLetter = disk["CAPTION"].ToString() + "\\";
                            else
                                driveLetter += ";" + disk["CAPTION"].ToString() + "\\";
                        }
                    }
                    if (!String.IsNullOrEmpty(driveLetter))  //check was added to ignore linux partitions
                        partitionedDrives.Add(driveLetter);
                }
            }
            catch (Exception)
            { partitionedDrives = null; }
            return partitionedDrives;
        }   //ends private ArrayList GetPartitionInfo(...

    }
}